Silk Fibroin/Polyvinyl Pyrrolidone Interpenetrating Polymer Network Hydrogels

Silk fibroin hydrogel is an ideal model as biomaterial matrix due to its excellent biocompatibility and used in the field of medical polymer materials. Nevertheless, native fibroin hydrogels show poor transparency and resilience. To settle these drawbacks, an interpenetrating network (IPN) of hydrogels are synthesized with changing ratios of silk fibroin/N-Vinyl-2-pyrrolidonemixtures that crosslink by H2O2 and horseradish peroxidase. Interpenetrating polymer network structure can shorten the gel time and the pure fibroin solution gel time for more than a week. This is mainly due to conformation from the random coil to the β-sheet structure changes of fibroin. Moreover, the light transmittance of IPN hydrogel can be as high as more than 97% and maintain a level of 90% within a week. The hydrogel, which mainly consists of random coil, the apertures inside can be up to 200 μm. Elastic modulus increases during the process of gelation. The gel has nearly 95% resilience under the compression of 70% eventually, which is much higher than native fibroin gel. The results suggest that the present IPN hydrogels have excellent mechanical properties and excellent transparency.This work was supported by The National Key Research and Development Program of China (Grant No. 2017YFC1103602), National Natural Science Foundation of China (Grant No. 51373114, 51741301), PAPD and Nature Science Foundation of Jiangsu, China (Grant No. BK20171239, BK20151242).info:eu-repo/semantics/publishedVersio

Selective Loss of Cysteine Residues and Disulphide Bonds in a Potato Proteinase Inhibitor II Family

Disulphide bonds between cysteine residues in proteins play a key role in protein folding, stability, and function. Loss of a disulphide bond is often associated with functional differentiation of the protein. The evolution of disulphide bonds is still actively debated; analysis of naturally occurring variants can promote understanding of the protein evolutionary process. One of the disulphide bond-containing protein families is the potato proteinase inhibitor II (PI-II, or Pin2, for short) superfamily, which is found in most solanaceous plants and participates in plant development, stress response, and defence. Each PI-II domain contains eight cysteine residues (8C), and two similar PI-II domains form a functional protein that has eight disulphide bonds and two non-identical reaction centres. It is still unclear which patterns and processes affect cysteine residue loss in PI-II. Through cDNA sequencing and data mining, we found six natural variants missing cysteine residues involved in one or two disulphide bonds at the first reaction centre. We named these variants Pi7C and Pi6C for the proteins missing one or two pairs of cysteine residues, respectively. This PI-II-7C/6C family was found exclusively in potato. The missing cysteine residues were in bonding pairs but distant from one another at the nucleotide/protein sequence level. The non-synonymous/synonymous substitution (Ka/Ks) ratio analysis suggested a positive evolutionary gene selection for Pi6C and various Pi7C. The selective deletion of the first reaction centre cysteine residues that are structure-level-paired but sequence-level-distant in PI-II illustrates the flexibility of PI-II domains and suggests the functionality of their transient gene versions during evolution

On the study of vibration of a supported railway rail using the semi-analytical finite element method

An improved rail vibration model based on the semi-analytical finite element (SAFE) method has been developed, which allows multiple layers of support and the accurate shape of the rail cross-section to be considered in the modeling. Rail supports are treated as a continuous layer of equivalent springs connected to the rail foot. Three different assumed support conditions corresponding to no support; rail pads; and rail pads, sleepers and ballast have been modeled. By determining the track parameters from a field test, this model is demonstrated to be able to determine the dispersion relations and the forced responses of both free and variously supported rails. Further, the effect of rail damping including frequency-dependent viscous damping and frequency-independent structural damping on rail vibration responses is investigated. The effect of the adopted discretization strategy on the calculation is also studied. Model results are compared with predictions from the Timoshenko beam-based rail models with the same support conditions. The results show that track support dynamic stiffness can be incorporated into the developed SAFE rail model which can then be used to represent the real track situation at a site; the rail support can significantly affect rail dispersion and frequency responses below 1. kHz; the Timoshenko beam-based rail models provide an inadequate prediction of rail vibration response, particularly in the lateral direction, if response at specific frequencies is required; the rail damping has limited impact on rail vibration responses; and the number of elements has insignificant effect on the calculated rail responses and wave dispersion relations, especially away from the excitation point

Reliability analysis and optimization of modular converter system of wind turbines in design

Modular converter has been gaining in popularity in converter system design for modern wind turbines in order to achieve high reliability and cost-effectiveness in service life. In this study, the reliability and optimization of a novel topology of fault-tolerant modular converter system are investigated. In this architecture, a converter system comprises identical and interchangeable basic modules. Each basic module can operate in either AC/DC or DC/AC mode, depending on whether it operates on the generator side or the grid side. Moreover, each module can be reconfigured from one side to the other, depending on the system\u27s operational requirements. This paper focuses on the system optimization of the modular converter system with considerations of life cycle cost and performance. Both Markov model and Monte Carlo simulation are utilized in system reliability analysis. Due to stochastic characteristics of wind speed, a converter system is allowed to operate under a degraded state in this study in order to increase the cost-effectiveness in designed life. The approach developed in this paper is applicable to seeking the optimal solution of other fault-tolerant systems in design stage by considering performance and life cycle cost

The Study of Fuzzy Proportional Integral Controllers Based on Improved Particle Swarm Optimization for Permanent Magnet Direct Drive Wind Turbine Converters

In order to meet the requirements of high precision and fast response of permanent magnet direct drive (PMDD) wind turbines, this paper proposes a fuzzy proportional integral (PI) controller associated with a new control strategy for wind turbine converters. The purpose of the control strategy is to achieve the global optimization for the quantization factors, ke and kec, and scale factors, kup and kui, of the fuzzy PI controller by an improved particle swarm optimization (PSO) method. Thus the advantages of the rapidity of the improved PSO and the robustness of the fuzzy controller can be fully applied in the control process. By conducting simulations for 2 MW PMDD wind turbines with Matlab/Simulink, the performance of the fuzzy PI controller based on the improved PSO is demonstrated to be obviously better than that of the PI controller or the fuzzy PI controller without using the improved PSO under the situation when the wind speed changes suddenly

Performance of Washing-Free Printing of Disperse Dye Inks: Influence of Water-Borne Polymers

Dye-containing wastewater discharge from the textile industry poses a serious pollution hazard that can be overcome by eliminating the washing step following the dyeing process. To study the washing-free printing of disperse dye ink, a number of water-borne polymers were selected and added to the ink, and the properties of the inks were discussed. By optimizing the ink formulation, printed fabrics with high color strength and color fastness were produced. The effects of the addition of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and polyethylene glycol (PEG) on the ink jetting performance and printing performance were intensively investigated. The migration–diffusion–fixation behavior of disperse dyes in inks on the polyester fiber was explored. The disperse dye ink with 0.075 wt.% PVA exhibited the strongest migration–diffusion effect. The PVA ink exhibited excellent jetting performance and printing color fastness, and the printing color strength was better than that of the PVP and PEG ink. The addition of PVA increased the difference between the solubility parameter of the disperse dyes and ink system, which improved the migration of disperse dyes from the ink system to the polyester fabric. Meanwhile, PVA could form a protective layer on printed fabrics because of its excellent film-forming properties at room temperature. The washing-free inkjet printing method developed in this study provides a theoretical basis for screening water-borne polymers and an environmentally friendly pathway for the printing of textiles

TA–Fe(iii) complex coated PS nanospheres for non-iridescent structural coloration of cotton fabric

Photonic structures constructed from colloidal nanospheres present an attractive prospect for structural coloration in an ecological manner. However, the application of structural color in the field of textile coloration is usually blocked by their uncorrelated scattered light and feeble mechanical properties. Here, a non-iridescent structural color coating with high color saturation and mechanical stability is developed by assembling PS@TA-Fe(iii) core-shell nanospheres. The rough surface and low surface charge are favorable for forming amorphous colloid arrays (ACAs) by restricting the crystalline alignment during the assembly process, resulting in non-iridescent structural colors. In addition, the as-prepared structurally colored cotton fabric possesses high color saturation and mechanical stability thanks to the intense light absorption and interface adhesion of the TA-Fe(iii) shell. The preparation approach of this structural color coating is facile, low-cost, and environment-friendly, showing promising applications in textile coloration and smart displays

Comparison study on dye degradation by PDA-SF/AgNPs-H2O2 and PDA-SF/AgNPs-PMS catalytic system

In this work, polydopamine (PDA) was used to facilitate the reduction of silver nitrate (AgNO3) to silver nanoparticles (AgNPs) and the simultaneous loading on waste silk fabrics (PDA-SF/AgNPs). The removal activity of the obtained composite PDA-SF/AgNPs on different dyes in the presence of hydrogen peroxide (H2O2) and potassium peroxymonosulfate (PMS) was compared. The effects of reaction temperature, H2O2/PMS dosage, dye concentration, composite dosage, electrolyte concentration and time in two catalyst systems on the dye removal were discussed. The results showed the dye removal of Telon Red A2R reached 81% and 95% in 30–50 min in PDA-SF/AgNPs-H2O2 and PDA-SF/AgNPs-PMS system, respectively. Quenching experiments demonstrated that ·OH, ·O2– and SO4-· were produced during the degradation process, and the possible degradation pathway of Telon Red A2R were analyzed by HPLC-MS. In addition, the kinetic study indicated that the removal of dye followed quasi-second-order adsorption kinetics. These findings suggest that fabric-based composites have great potential and applications in catalysis and treatment of wastewater

The Prevalence of Reproductive Tract Infections in a Chinese Internal Migrant Population, and Its Correlation with Knowledge, Attitude, and Practices: A Cross-Sectional Study

Objective: This study was designed to assess the prevalence of reproductive tract infections (RTIs) among an internal-migrant population of reproductive age in China. We also analyzed the knowledge, attitude, and practices related to these infections. Methods: A cross-sectional study using the quota-sampling method was conducted in three cities from March 2016 to February 2017. A total of 3320 participants (40.7% men and 59.3% women) were enrolled in the study, of whom, 1124, 1015, and 1181 were from Yinchuan, Urumchi, and Shanghai, respectively. Data on the included subjects were collected using a self-administered questionnaire. Results: We found that 3.2% and 22.6% of all subjects lacked knowledge regarding the identification and prevention of RTIs, respectively. More than 80% of the participants approved of developing RTI surveillance and taking RTI-related courses. While 45.1% of the respondents changed their underwear every 2⁻3 days, 49.0% cleaned their genitals daily, and 34.9% reported taking a bath daily. Among contraceptive users, 47.4% and 29.7% used condoms and IUDs (intrauterine devices), respectively. Overall, 48.2% of the participants had laboratory-confirmed sexually transmitted infections, and 19.7% of the female participants had endogenous infections. After controlling the socio-demographic variables, participants who cleaned their genitals and took a bath less frequently, as well as used condoms or pills had a lower prevalence of sexually transmitted infections, while those who were unwilling to take RTI-related courses and changed their underwear less frequently were more likely to contract sexually transmitted infections. While women who were unwilling to take RTI-related courses had a lower prevalence of endogenous infections, those with more children had a higher prevalence. Conclusion: The status of RTIs among the internal-migrant population of reproductive-age is not optimistic and is related to multiple factors. We believe this study will contribute to improving the knowledge, attitude, and practices related to RTIs